In many industries there is much interest in monitoring carbon monoxide (CO) levels during industrial processes, specifically when balancing ratios of oxygen (O2) to fuel during combustion. When unable to monitor CO levels manufacturers tend to run lean in order to avoid explosions. However, this results in engine knocking and can lead to formation of NOx species. By monitoring CO levels an ideal balance of O2 to fuel may be maintained, thus avoiding knocks and minimizing pollution. Existing gas sensors are made from metal oxide-based materials that usually are not selective but rather will respond indiscriminately to a broad spectrum of reactive gases. In addition to an indiscriminate response, state of the art detectors and sensors made from such metal oxide-based materials will often exhibit unstable baseline resistance, continuous drift, and poor recovery time.
There is a need for new materials that exhibit selective changes in their properties in the presence of CO or other hydrocarbon gases and that respond selectively to CO, and for new low drift detector and sensor devices made from such materials that also respond selectively to gases such as CO or other hydrocarbon gases. Additionally, a need exists for materials, detector and sensor devices, and methods employing these devices for CO detection and measurement that are more economical than the current materials and methods used to detect and measuring CO. Currently, there is a need for new solid state CO sensors useful for optimizing fuel efficiency in a variety of industrial processes and a need for new materials useful for making CO sensors that can be used to measure local CO concentrations in combustion chambers or in other hostile industrial environments where temperatures between 450-700° C. are reached. Sensors for use in these hostile environments should be able to detect and measure CO present at concentrations as low as sub-ppm level. Sensors for use in these hostile environments should also exhibit minimal drift and quick recovery times.